The present invention relates to a MIM (Metal-Insulator-Metal) capacitor.
In recent years, for example, the plausibility of forming an RF analog device and CMOS logic device on one chip is being examined. The RF analog device includes a resistor, coil, and capacitor, whereas the CMOS logic device is formed from a MOS transistor.
To form an RF analog device and CMOS logic device on one chip, the manufacturing processes of these devices must be integrated. For example, the process of the RF analog device is integrated based on the CMOS logic process to develop a new RF-CMOS process.
The first problem in integrating the processes is the structure and process of a MIM capacitor. For example, when the gate length of a MOS transistor is 0.1 μm or less, the use of Cu (copper) as a wiring material is examined to reduce the wiring resistance and the like.
However, Cu has a large diffusion coefficient. When, therefore, a MIM capacitor having a Cu electrode is formed, Cu diffuses into a capacitor insulating film to increase the leakage current.
When Cu is used as a wiring material, a Cu wiring line is formed by a so-called damascene process because of the processing precision and flatness. At this time, the electrode of the MIM capacitor is also formed by the damascene process, and thus suffers problems caused by the damascene process, e.g., dishing and reduction in electrode area in avoiding dishing.